LITTLE ROCK, Ark. (AP) - The lawmakers proposing to ban most abortions in Arkansas at 12 weeks into a pregnancy on Tuesday said they'll change the measure to add more exemptions and remove criminal penalties for doctors who violate the restriction.

The House delayed a vote on the legislation, which had been expected Wednesday, after Sen. Jason Rapert and Rep. Ann Clemmer said they wanted to make changes to the proposed ban. If enacted, it would be one of the strictest abortion bans in the country.

Gov. Mike Beebe, a Democrat, has called the ban unconstitutional but has not said whether he'd veto the legislation if it reaches his desk.

The legislation would ban abortions 12 weeks into a pregnancy if a fetal heartbeat is detected using an abdominal ultrasound, with exemptions for rape, incest and risk to the mother's life. Rapert and Clemmer on Tuesday proposed adding exemptions for medical emergencies and for "highly lethal" fetal disorders. The proposed amendment would leave it up to the Arkansas State Medical Board to define such disorders.

Rapert, R-Conway, said his intention had been to include medical emergencies as an exemption, but said it had been left out because of a drafting error.

"We simply want a bill that's going to save lives in the state, but also not be involved in issues that are very difficult for families to begin with," Rapert said. "I think these are appropriate, and it actually brings more support to the bill."

The proposals mark the second time that Rapert has proposed changing the bill. The original version passed by the Senate would have banned abortions as early as six weeks into a pregnancy. Opponents said the only way to detect a heartbeat that early would have been by using a vaginal ultrasound.

The changes proposed Tuesday mean the bill will head back to the House Public Health, Welfare and Labor Committee, where Democrats hold 11 of 20 seats. Republicans hold a majority of seats in the House and Senate.

The amendment filed Tuesday also would remove the criminal penalties for doctors who perform abortions in violation of the 12-week ban. The legislation had originally made violation by doctors a felony punishable by up to six years in prison and a fine of up to $10,000. Doctors could have their medical license revoked by the state Medical Board if the panel finds them in violation under the changes proposed Tuesday.

A spokesman for Beebe said the governor's objections have focused more on the concern that the measure would run afoul of the U.S. Supreme Court's 1973 Roe v. Wade ruling that legalized abortion up until viability, usually at 22 to 24 weeks.

"I think the governor's constitutional concerns continue to center around the 12-week viability claim, which goes against other previously established rulings," Beebe spokesman Matt DeCample said.

Clemmer, R-Benton, said the bill is aimed at pushing the envelope on constitutional law surrounding abortion.

"Judges don't typically rule unless a law is passed first," she said. "We believe that it is time for the court to look at it."

Other "heartbeat" abortion bans have fallen short in statehouses elsewhere. The North Dakota House last week approved a "heartbeat" abortion bill that would ban the procedure as early as six weeks, and the measure is now pending before the state Senate there.

The sponsor of another abortion restriction in Arkansas said Tuesday he also planned to change his proposal. Rep. Andy Mayberry, R-Hensley, said he'll add rape and incest exemptions to his bill banning abortions 20 weeks into a pregnancy.

Mayberry said he planned to bring his bill before the Senate Public Health, Welfare and Labor Committee on Wednesday. The panel is equally split between Democrats and Republicans, and Mayberry said he didn't believe he could get his proposed ban out of committee without the exemptions.